Using the techniques of molecular cloning, we propose to isolate and characterize plasmids harboring sequences complementary to proline-rich protein messenger RNA induced in the parotid glands of rats following injection of animals with the beta-adrenergic drug isoproterenol. The plasmids will be employed as hybridization probes for the identification of genomic clones containing the structural information for proline-rich proteins. The genomic clones and the cDNA plasmid clones will be studied structurally by the techniques of restriction endonuclease site mapping and DNA sequencing. Both types of clones will be employed to investigate the mode of action of isoproterenol in a variety of mammalian tissues.